Multi-channel transponder



July 20, 1965 s. woLF ETAL MULTI-CHANNEL TRANSPONDER 9 Sheets-Sheet 1 Filed April 22, 1963 ATTORNEY 9M AGENT Q BY i; l Q

s'lanNvHo uaonasnva July 20, 1965 s. WOLF ETAL 3,196,199

MULTI-CHANNEL TRANSPONDER Filed April 22, 1963 9 Sheets-Sheet 2 CHANNEL CHANNEL 2 CHANNEL 3-6 CHANNEL 7 CHANNEL 8 July 20, 1965 s. WOLF ETAL. 3,196,199

MULTI-CHANNEL TRANSPONDER Filed April 22, 1963 9 Sheets-Sheet 3 CHANNEL 2 DELAY /oea/ cHANNEL s-e DELAY /oaa/ CHANNEL 7 DELAY /oeb/ cHANNEL I; /08 DELAY j /oeb/ /07 FIG. 2b

July 20, 1965 s. woLF ETAL 3,196,199

MULTI-CHANNEL TRANSPONDER Filed April 22, 1963 9 Sheets-Sheet 4 PQR? smreaomn 2c OSCILLATGR July 20, 1965 Filed April 22, 1963 9 Sheets-Sheet 6 R F W CARRIER OSO l LLATOR 530 ECHO DELAY-TIME MODULATOR NGISE GENERATOR FIG. 2e

July 20, 1965 s. woLF ETAL MULTI-'CHANNEL TRANSPONDER 9 Sheets-Sheet 8 Filed April 22, 1963 BB FINE D'EPTH 50H0 ATTENuATloN COARSE DEPTH ATTENUATION F INE DE PTH CONTROL ECHO OUTPUT July 20, 1965 s. WOLF ETAL 3,196,199

MULTI-CHANNEL TRANSPONDER Filed April 22, 1965 9 Sheets-Sheet 9 CHANNEL l CHANNEL 2 TO COARSE DEPTH RESETTING POINT ECHO GATE United States Patent O The present invention relates to a system for simulating certain water characteristics to be utilized as information in a computer for determining such things as underwater launch correction `factors for missiles.

l'n general, devices have been provided in the prior art for determining the characteristics of variable conditions ot water, such as its depth, prior to launching of a missile therefrom, Typical prior art devices for determining the state of water and of objects in the water are generally referred to as sonar systems. In order to effectively train operators of these various devices, it is desirable to provide a system to inject controlled hypothetical information indicating varying conditions into the computing device so that a student operator can be trained under varying conditions. It is further `desirable that the information controlling system be located outside of the actual working conditions under which a normal system would operate in order that a convenient teaching facility may be provided.

Systems have been provided in the prior art for simulating detected objects in typical sonar applications. However, a need has arisen -tor a simulation device for training purposes in the newly developed underwater missile launch technology. Such a device should be able to simulate hypothetical conditions to which the various sensors for determining water characteristics will be subjected.

Therefore, it is an object of the present invention to provide a system for simulating water depth and surface characteristics in a hypothetical underwater missile launch situation.

lt is a further object of the present invention to provide a transponder system for providing hypothetical water depth and Wave motion data to a plurality of transducers in connection with water condition sensing means.

Another object of the present invention is to provide a transponder system having a plurality of inputs and outputs for receiving interrogating signals and transmitting hypothetical dept-h and wave motion echo signals t a water characteristics computation system.

Still another object of the present invention is to provide a transponder system having a plurality of inputs adapted to be energized in sequence and adapted to eliminate cross-talk between parallel inputs.

A further object of the present invention is to provide a transponder system having a plurality et inputs which are designed to simulate transducer channels in a water characteristic measuring system, are connected electrically to an echo simulating circuit, and are energized in sequence to provid-e hy ilietical water characteristic depth an... wave motion iA a cation to a water condition sensing system.

Still another object of the present invention is to provide a transponder system having a plurality of input channels connecting `a water characteristic computer to a water depth simulating system which is designed to provide simulated echo pulses which may be varied to indicate varying water depths and surface Wave motion.

The present invention is designed to provide a transponder system for simulating echo pulses fed into a water condition sensing system, such as that used in underwater missile launch operation, whereby a plurality of transducers located, hypothetically, along the surface of a submarine are energized in sequence to transmit and receive ice echo pulses indicative of water depth and wave motion. The present system relates only to the water depth transponder system and is designed to provide an operator with water depth information which is variable for varying hypothetical conditions. The transponder system is designed to receive interrogating pulses from a separate water condition computer in sequence in each of several inputs which are designed to simulate transducers located on a submarine. These simulated transducers operate, in sequence, to interrogato an echo pulse simulating system which in turn provides an output pulse which is a hypothetical echo back to the transducer indicative to Water depth and wave motion.

Other objects7 advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the 'accompanying drawings wherein:

FIG. l is a block diagram of the transponder system;

Pi-S. 2x1-g are detailed drawings of the transponder system showing circuit diagrams of certain parts of thS system;

FIG. 3 is a timeline chart showing the relationship of the various signals within the system from the transmit pulse to the echo pulse.

Reference is now made to FIG. l wherein is shown a blocl; diagram of Vthe present transponder system. A plurality of inputs ldd are provided Iinto the transponder system. These inputs simulate a plurality of transducer channels which, in practice, are energized by a water condition computer. a sampling resistor itil. to sample the input interrogating pulse to the system which is a hypothetical transducer actuating pulse from the water condition computing system. These sampling resistors lidi provide an input signal t0 a detector and antisnormalization circuit M92, each of these circuits MBZ being designed to simulate a transducer located in a predetermined point on a submarine. The purpose of the anti-normalization circuits is to simulate a transducer which is located at a predetermined point on a submarine rather than on the normalization line for the system. It should be noted that, in general, a Water characteristic sensing system incorporates a normalization system to compensate for varying relative depths of the transducers. This normalization system adjusts the effective depth of each of the transducers to a predetermined common depth such as the keel line of the ship. Since the condition sensing system utilized in conjunction with the present transponder system generally incorporates normalization means, the anti-normalization circuits 132 are necessary to simulate diiterences in hypothetical transducer depths. in order to simulate transducers located at the same depths on a submarine, a plurality of inputs litio connected in parallel are provided to a special detector and common anti-normalization circuit 1% which will be hereinafter more particularly described. In general, the purpose of this circuit is to eliminate cross-talk between inactive channels due to the increased capacitance of the inputs connected in parallel when another channel is activated. Each of the several detector and anti-normalization circuits 102 and w3 are connected at their outputs to an OR gate ltll. The purpose of OR gate ltliis to provide a common output from the detector and anti-normalization circuits i432 and 193 upon excitation of each in sequence.

it should be noted that the means for sequentially eX- citing each transducer channel is provided in the condition computing system itself and is not a part of the present invention. Por purposes of the present invention any system having a normalization means which is capable of exciting the transducer channels in sequence `and receiving echo pulses could be utilized.

OR gate ldd is connected to transmit-receive relay Each input has connected thereto driver 105' which in turn actuates a switch arm 1697 to connect the inputs of the transducer channels 1G19 and 106 to either dummy load 193 or pulse amplifier 109- As shown in FIG. 1, the transducer channels 'are connected to pulse amplifier 109, which is the receive mode of operation of the system. In its original transmit condition7 i.e., when the hypothetical transducers are in position to receive interrogating pulses, switch arm 107 iS connected to dummy load 1% to simulate a normal load presented to the transducers.

As will be hereinatferimore particularly described, the output of each detector and anti-normalization circuit 102 is a pulse. The leading edge of this pulse is adapted to actuate transmit and receive relay driver 105 and the trailing edge of the pulse actuates the coarse depth simulator circuits, A, B, or C. These circuits are connected to OR gate 104- by a switch 111 which may be positioned to contact any of the three course depth simulators. The purpose of a plurality of coarse depth simulators is to indicate a variety of depths, any one of which may be selected by positioning the switch 111. Coarse depth 'simulator C is nothing more than a short circuit, and will impose no delay in the echo simulating system. The coarse depth simulator is connected to a special resetting Sanotron 112, this circuit being designed to provide a tine depth delay in the echo system, and is acted upon by signals from a low frequency oscillator 114 and a noise generator 11S which signals are mixed in mixer 116 to indicate wave motion and noise factors which would be present in any practical system. Mixer 116 is acted upon by a fine depth control 123, and provides amplitude modulation to gated ampliiier 1115 which amplifier receives an -RF .carrier signal from oscillator 119. The output of Sanotron 112 is gated to coarse depth attenuator through gate circuit 117. RF oscillator 119 provides the basic signal which is passed through gated amplifier 11S to coarse depth attenuator 121, tine depth attenuator 122 which is mechanically adjustable by fine depth control 123, to pulse amplifier 109 and thence to the computer system through inputs 100.

As has been previously mentioned, each of the transducer channels are provided with a separate detector and anti-normalization circuit 102 except in cases where the simulated transducers are located, hypothetically, at the same datum levels with respect to the normalization level of the system. The reason for providing separate indicator and anti-normalization circuits for each channel is that each anti-normalization circuit should be designed to .simulate transducers located at different levels with respect to the normalization level of the system. In cases where the simulated transducers are located at the same levels, it is desirable to connect each input 1% in parallel with a single detector and a common anti-normalization circuit. It may be appreciated that although each channel is connected in sequence to transmit and receive information, the capacitance of the disconnected channels will cause a certain amount of cross-talk to a signal incoming on the connected channel. As will be more clearly pointed out later, the output signal of each detector circuit tla is a spike pulse. This pulse is used to trigger the anti-normalization circuitry 10211 which circuitry is designed to be actuated only when the spike pulse reaches a predetermined level of amplitude. As can be seen by reference to the output of the detector circuit 1il2a in FIG. 2a, the echo pulses due to the single capacitance feedback from disconnected channels are not :of suicient magnitude to trigger the antinormalization delay circuits 16211. However, the parallel connected common depth transducers having common inputs 1% will have a combined additive effect and provide cross-talk pulses of sufficient magnitude to interfere with the operation of t-he anti-normalization delay circuitry. Thus, it is necessary to provide a special circuit for eliminating the combined capacitance effect of the parallel connected circuits. This special circuitry is the subject matter of application Serial i Number 274,877 tiled April 22, 1963 by Samuel Wolf and Roy C. Robley, Jr.

Referring now to FIGS. 2a through 2g, there is shown -a more detailed drawing, partially in block and partially in schematic, of the transponder system of the present invention. Since several of the circuits are duplicated for the multiplicity of input channels, only a single circuit will be described where appropriate. As may be seen in FIG. 2a, the single input channels 160 and multiple input channels 106 are connected into the detector circuits 1il2a and 103a, respectively. For simplicity only a single detector circuit 162er will be described in detail and the corresponding detector circuits for single input channels are merely shown in block form.

As shown in FlG. 2a, the input 1% to the transducer channels are coupled to a pair of sampling resistors isili) each located on one side of the input. The reason for providing a sampling resistor 464B and a detector circuit 1t2a on each side of the line is to provide a balanced circuit. Sampling resistors 46d are designed to provide a voltage drop indicative of the input to the channel. This voltage signal is coupled to a transformer N11 having a primary and secondary winding. The secondary Winding of transformer 491 is coupled through diode 4%2 and capacitor dit@ to the input of anti-normalization delay circuit 12b through line 4% and capacitor 11% (FlG. 2b). The anti-normalization circuits 1Mb are designed to provide a delayed output signal and is a standard multi-vibrator circuit. The inputs 19t) and 166 are connected via lines 410 and 411 shown in FIG. 2a to a dummy load 108 through switch arms 107 shown in FIG. 2b when the transducer system is in the transmit mode of operation, i.e., when the transducers are hypothetically adapted to be energized by an interrogation pulse. Upon actuation of the relay driver by an output pulse from one of the anti-normalization circuits 102b in a manner hereinafter to be more particularly described, relay driver 165 will be de-energized to allow switch arms 167 to move the receive mode of operation to allow a simulated echo pulse to be returned through inputs to the water characteristics computer system.

Referring again to anti-normalization circuits 1'll2b shown in FIG. 2b, it may be seen that these circuits are comprised of multi-vibrator 467 comprising a dual triode Ai12 having the plate of one triode connected through capacitor d66 and diode 413 to the detector circuit ltlZa. The grid of the second triode is connected to the plate of the first triode through capacitor 414. Resistors 416 through 421i are standard multi-vibrator circuitry to provide the proper bias and switching action of the multivibrator 407. A voltage divider comprising resistor 417, potentiometer 422 and resistor 423 provides the bias to the grid of one of the triodes. Capacitor 424i provides the A.C. bypass for the grid of one of the triodes. Resistor 426 provides the cathode potential for the multi-vibrator tubes.

The output of detector 102e or 163m, when one of these is actuated in sequence, provides a negative going pulse to the input of the multi-vibrator 467. This pulse is shown in FIG. 2a. As may be seen by reference to this signal, a small amount of cross-talk due to the input capacitance of the various circuits causes a number of ghost pulses of small amplitude. It is noted, however, that these cross-talk pulses are of insufiicient amplitude to trigger the multi-vibrators 407. However, in the multiple, parallel connected channels 106, the cross-talk signals may achieve suiiicient amplitude to trigger the multi-vibrator and thus interefere with the proper operation of the circuit. A special detector circuit, previously referred to, must be provided if multiple parallel connected channels are desired.

As can be seen by reference to FIG. 2b, the input trigger signal to any of multi-vibrators 467 results in an output signal which is a square wave pulse. The relationship of this pulse, which is referred to as a delayed signal, to

the trigger pulse may be seen by reference to the timeline chart shown in FlG. 3. The delay pulse from the output orC each anti-normalization circuit ltlb simulates a variation in the depth of the hypothetical transducers trom the normalization line of the system. This signal is RC coupled to relay driver llilS through an integrator comprising capacitor 427 and resistor 42d and a diode 429. As may be seen by reference to the drawings, FlG. 2c, the output signal ot integrator is a tast rising pulse. This pulse is coupled to relay driver lltiS by capacitor 4.3i and resistor dit?, to provide a bias to triode 433. Diode 435 provides a bypass for the input to triode Upon actuation ol triode 433, the square wave output at its plate is coupled through the parallel combination of capacitor and resistor 37 to the grid oi one of the dual triodes of switching circuit 433. Switching circuit 43S is a standard circuit and will not be described in detail. lt is seen, however, that energization of the circuit provides a positive output pulse which is coupled through the parallel combination of capacitor 439 and resistor All to cathode follower This positive pulse provides a bias to the grid ol cathode follower 42 which in turn begins to conduct and generates a voltage drop across cathode resistor ot the same duration as the input pulse. This voltage drop is coupled through resistor ddd to the base of a transistor which is provided with an overload protection oiode l :E connected to a bias potential. Receipt of the pt lse at the base of transistor biases it to cutoh to thereby open the circuit from the power supply lf-ll as shown in FlG. 2d through the relay coil t4-'7 of the switching circuit to thereby de-energize the relay and relay and release switch arm lo? as has been hereinbefore crib-cd. Eiode dal@ provides protection for relay coil "3. Power supply is a standard power supply and is shown only in blocl; torni.

As has been previously mentioned, the outputs or" the anti-normalization circuits id21) are fed to the relay driver lili and the coarse depth circuit lill through diodes 429 and 43h, respectively. By reference to FlG. 2b it can be seen that the polarity of diode enables only the leading edge or positive portion of the delayed pulse to pass into the relay driver circuit ldd'. On the other hand, diode transfers the trailing edges or the negative portion of As shown in the drawings, coarse depth delay cirlll has three separate delay times which may be selected by positioning a switch. These three delay times are indicated by contacts A, B, and C on the input and output portions of the circuit. Contact A provides access to a delay multi-vibrator M9, Contact B provides an input to delay multi-vibrator 45d, and contact C provides an input to a standard transmission line which incorporates no delay into the circuit. Delay multi-vibrators dtd-9 and are standard multi-vibrator circuits, and further description is not deemed necessary to an understandin?` of the present device. lt need only be mentioned that each circuit may be adjusted or designed to provide a predetermined delay signal.

The output of the coarse delay circuit lill is a square rvs-ve pulse as shown in FIG. 2c and is coupled into an .o delay time modo ttor i312, termed a special resetting Sanotron, shown in FIGS. 2d and 2e, which provides a line adjustment on the time delay for the simulate.-. echo pulse. Echo delay time modulator E52 includes a run-down gate generator lil-4l comprising a reset entode tube E55 and a dual triode switching tube 456. l Miller run-down circuit actuates a dual triode witching circuit which is cathode connected to the .rid of one triode of a dual triode comparator circuit The output of coarse `depth delay circuit 451 is coupled to the echo delay time modulator d?, through a capacitor 462 which couples the signal through diode to the plate of resetting pentode 45S and thence to the grid of first triode of the dual triode switching circuit The plate of the first triode is coupled to the grid to? of second triode 46d through the parallel combination ot resistor 47@ and capacitor 6371. The supply voltage for the pentode and the triode switching circuit is supplie-d through resistors 472, 473, 1374i-, 475, and die. Dual triode switching circuit 456 is cathode connected to the suppressor grid d@ of pent-ode thi `which is the tube `lor the Miller rundown circuit 458. lt should be noted that resistor 4E-i7 provides the voltage drop in the cathode circuit of triode d68 which is coupled to the Miller run-down generator ddd. The grid bias for the run-down circuit is obtained from resistor ddii, potentiometer and resistor through dropping resistor Capacitor 437 provides AC. coupling to the supply voltage. The screen grid of pentode is biased through resistor to the cathode of triode 492 .of the dual triode 493. Resistor 41:91 in the cathode circuit provides the voltage drop, while capacitor 49d provides the AJC. bypass tor the cathode of triode SQE. Resisotr which is coupled to the cathode of triode d-92 provides the plate supply for pentode ddl. The output of Miller run-down is connecte-d to the grid 599 ot triode of the dualtriode switching circuit The dual triode is cathode coupled to comr do@ by resistors @l and fidi-l for triodes 492. .nd 4%, respectively. @ual triodes fr.' and dit?. provide comparator circuit for comparing `the output voltage.` ot the run-down circuit with a reference voltage. As can be seen by reference to the drawing, FlG. 2e, the output or' comparator circuit is coupled through capacitor 03 and lead to the suppressor grid of reset pentode WS, This feature of the present invention is of the utmost imnortance to the device since the output spike pulse ot the comparator circuit actuates pentode del which causes the output signal .to reset dual triode switching circuit and thus provide an output pulse. This output signal is coupled through lead 5% to -an echo width pulser dud, shown in FlG. 2f, which will Le hereinafter more particularly described.

A variation of the reference voltage tor comparator circuit is obtained by means of unction generators l lo, shown in FlG. 2c, and lldb, shown in FIG. 2d, along with noise generator MS, shown in 2e. These signals are .mixed in mixer als, shown in FIG. 2f, and are coupled to comparator circuit to cause a variation of the ,reference voltage and thus a variation of the depth simulation of the echo pulse. lt should be pointed out that the Miller run-down generator is reset by switching circuit and reset pentode and. The reset signal issues from compa ator au@ when the reference voltage and the voltage `ot `the run-down geuerator are eci-ual. By adjustin the reference voltage, control of the level of the tine depth adjustment is obtained. lt readily appare t, ther re, tn t function generators Slide and lll-tb, and noise generator lid, provide a simulated varying depth for the echo pulse which may he indicative of water surface motion. A typical example of function generators would be a pair or" sine wave generators indicating fore-aft and port-starboard wave motion. However, any desirable function generators could be used in the present invention.

The une depth control of the present invention is obtained through fine depth control mechanism 123 shown in FlG. 2g which comp ses a triode circuit having a bias provided `by a variable potentiometer ""3 coupled to the grid ot the triode Further une adjustment of the fbias to the tube may be obtained through potentiometers Sil and Elli. The cathode of triode is coupled through resistor 5513 to the grid of pentode lz'e shown in FIG. 2f. lt should be noted that the grid of pentode 5.715 is further biased by the output of function generators lid and llo' connected through mixer llo. The amplication of this reference voltage is controlled initially by line depth control Sill/3. A mechanical linkage 51rd insure-s that the tine depth adjustment `of the ech-o attenuator llZL- is the same as that of the line depth control 123. The output of pentode SiS is amplified by triode 517 and is cathode coupled through connector 531.3 to the triode 502. of comparator 56E@ shown in FiG. 2e. This signal, `along with the bias signal from the tine depth control circuit 123, provides the reference voltage for the comparator 56d. Resistors 518 and ST9 provide the cathode connection to the supply circuit for triode Si?, and provide a voltage divider for the connection of the output of the cathode circuit of triode 517 through connector 9 to the suppressor grid of pentode 52S of gated amplifier M8.

The passage of the echo pulse and the circuitry for determining its characteristics will now be described. The basic echo pulse is an `RF signal Supplied by oscillator 119 shown in FIG. 2e. This pulse is coupled to the output circuit at the proper time through a gated amplifier lig, an echo gate lili, an echo attenuator E22, and an echo amplifier N9. Gated amplifier HS, shown in FIG. 2f, comprises a pentode 52S having its input grid connected to RF oscillator il@ through resistor 53) and variable potentiometer S31. The screen grid of pentode 523 is connected to the supply voltage through resis-tor 5.3i), and the suppressor grid is biased by the output of the line depth tuning circuit through capacitor 532 and inductor 533. The output of gated amplifier 118 is RC couple-d to echo gate il?. Echo gate M7 displays an open circuit to the output signal of gated amplier M8 until the gate is opened by a signal from echo width pulser Stl' which in turn is actuated by the reset signal from the echo delay time modulator M2. vEcho width puiser S695 is a standard multivibrator circuit and is coupled through capacitor 534 and lead 5th? to the cathode circuit of triode 46S in the dual tricde switching circuit 456. Upon resetting of the switching circuit 4555, the pulse is coupled to echo width .pulser 565 to cause the `switching circuit to be actuated and to generate a negative sign-al which is coupled through lead 535 to the suppressor grid of pentode 536 in echo gate M7. The output signal from echo width pulser 505 when coupled to the suppressor grid of pentode 536 biases the pentode to conduct and, thus, pass the output of pulse amplifier 118 to the input of echo attenuator T22. The plate supply voltage of pentode 535 is provided through resistor 537 .and the parallel tank circuit comprising capacitor 538 and variable inductor S39. Resistor 541 and capacitor 542 provide coupling for the output signal from echo width pulser 595 to the suppressor grid of pentode 536.

The RF output of echo gate it? is RC coupled through capacitor 543 and resistor 547, shown in FIG. 2g, to the echo attenuator 122 having a coarse depth attenuation connected to cathode follower 544 and a fine depth attenuation connected to cathode follower o. The plate of triode 544 is connected to the grid through resistor 546. Inductor 48 connects the plate of triode 54:4 to the plate supply voltage. The coarse depth attenuation of the cathode signal is achieved through a series of voltage dividers, any one of which may be selected according to the desired attenuation of the cathode signal to indicate depth attenuation for the echo signal. Switch 550 is designed to contact voltage dividers 551i, 552, 0r 553, which voltage dividers will provide different amounts of attenuation for the output signal. This attenuated signal is connected to the fine depth attenuator consisting of triode 556 and cathode potentiometer 557, through capacitor 555. The potentiometer 557 is connected by a mechanical linkage die to the tine depth control circuit 123 which has has been previously described in connection with the ne depth control of comparator Sti@ in the echo delay time modulation circuit. This mechanical linkage insures that the tine depth time delay of the echo signal corresponds with the attenuation of the signal to simulate a predetermined depth of the tranducer being interrogated.

The RF echo pulse output of attenuator T22 is coupled to the pulse amplifier til through an RC coupling circuit.

The pulse amplifier circuit itl@ may be any suitable amplifier circuit. A dual triode circuit wherein the output pulse signal is obtained from either of the cathodes of the triodes and coupled to the output through a transformer 55S is shown. As may be seen by reference to the drawings, FG. 2g, the echo output signal is a RF pulse of time delay determined by the interaction of the echo delay time modulation circuit, the echo width pulser, whose period of operation is determined by the resetting point on the Sanatron circuit and the echo gate circuit. The amplitude of the RF pulse is determined by the interaction of the coarse and fine depth attenuation circuits along with the pulse amplifier. As has been previously discussed, the echo output is coupled back through the hypothetical transducer circuit at the detector input, and thence transmitted to the utilization circuit which may be a water characteristic computer. The circuit described provides an echo pulse which is of a predetermined arnplitude and time delay indicative of the surface characteristie of a hypothetical body oi water proximate to the transducer outward. This type of simulator may be called a surface scanner transponder.

lReference may be made to the drawings, particularly FIG. 3 along with the detailed schematic in FTGS. 2 a through g, for the operation of the present invention. As has been previously mentioned, each of the transducer inputs litt? and 1% are connected separately in sequence to a utilization circuit such as a water characteristic computer. Tu normal operation, ie., where a typical transducer system on a submarine is operated, each transducer is excited by the utilization circuit and transmits a RF pulse which is refiected from the surface of the water and is received back into the transducer and thence transmitted to the utilization circuit to indicate the surface characteristic of the water.

The present device simulates such action by a hypothetical surface scanner circuit. Each input litt) or lite in the case of transducers located at common depth, is interrogated by a transmit pulse which is detected by sampling resistors d6@ and is coupled to an anti-normalization circuit tiZb from a detector ima. The input to each of the antinormalization circuits itZb is a spike pulse. As has been previously mentioned, the input capacitance of the disconnected inputs will cause a certain amount of cross-talk and in the case of a multiplicity of parallel connected inputs, the cross-talk reaches suiicient magnitude that a special detection circuit must be provided to eliminate the cross-talk. As shown in PEG. 2b, the excitation of an anti-normalization circuit llflb actuates a multi-vibrator circuit 407 which provides an output pulse indicative of a delay in the transmit pulse due to a variation in the relative location of the respective transducer. This output pulse is differentiated and the leading edge, which occurs almost simultaneously with the transmit pulse, is applied to the relay driver T05 which de-activates relay coil 44"? to switch arm 137 from dummy load TGS to its receive mode to be in position to receive simulated echo pulse. As may be seen 'oy reference to FIG. 3, relay driver de-activates relay coil 447 for a sufiiciently long time to allow the entire simulated echo operation to transpire. The trailing edge of the antinormalization pulse is applied through the OR circuitry to coarse depth delay circuit ltll which circuit delays the output pulse a predetermined length of time depending upon the delay circuit, to indicate roughly the depth of the transducer beneath the surface of the water. The coarse depth output signal is connected to the echo delay time modulator M2 which is designed to provide fine depth delay from the echo signal. This tine depth delay is achieved through the action of a Miller run-down 558 which is actuated by a rundown gate generator 454 and is applied to a comparator circuit Stitl. The comparator circuit Sil@ is supplied with a reference voltage which is modulated to indicate surface motion of water. The Miller run-down @58 generates a linear signal with amarcaico plitude decreasing with time until the rundown output Voltage is equal to the comparator reference voltage. At this time a reset signal is emitted from the comparator Stiti to reset the circuit. rlihe reset signal actuates switching circuit @.55 which circut emits a pulse whi .h is coupled through line to echo width puiser Sud. The length of the pulse into echo width puiser determines the time duration of the output pulse from echo width puiser since this circuit is a standard multi-vibrator circuit. The output of echo width puiser 5&5 is coupled to the suppressor grid of the pentode in echo gate lil'i'. rThe signal biases pentode 536 to conduct. A gated amplifier lill is connected to echo llll and is provided with an RF signal which is to be used as a simulated echo pulse. This. RF signal is coupled to gated amplier it, out will not pass to the attentuation circuit i212; except during the time that echo gate il? is conducting. Therefore, the length oi time that echo gate lll-" is open due to the action ot echo width puiser which in turn is actuated by the resetting Sanatron or echo delay time modulator M25.

The RF signal which passes through echo gate il? is attenuated by a coarse attenuator lid and a fine attenuator E253 in the echo attenuation circuit i222. This cir uit is adjusted by means of coarse attenuation switch 55@ and fine attenuation potentiometer Sdi' to limit the amplitude of the echo pulse to correspond `with the depth that has been previously determined by the time delay circuitry. rlhus, the echo pulse from the echo attenuation circuit is of a time duration and magnitude indicative of a pr determined surface condition of the water being scanned. The attenuated signal is coupled into a pulse amplier and thence through a transformer 53 to the echo output circuit. As may be seen by reference 'to the block diag ain oi FlG. l, switch arm lll? has been positioned to connect pulse amplifier to the detector circuits of the transducer channels le@ so that the proper echo pulse is coupled to the utilization circuit.

lt may be seen that the present invention provides a surface scanner transponder system for providing an RF echo pulse to a utilization circuit which is indicative of a predetermined hypothetical surface condition. This signal may be utilized in many different applications such as for teaching or demonstration.

Obviously many modifications and Variations of the present invention are possible in the light oi the above teachings. lt is therefore to he understood that within the scope of the appended claims the invention may be practiced otherwise than as specilically described.

What is claimed is:

In a sonar surface scanner transponder system, the combination comprising;

a plurality of signal receiving means simulating transducer channels, each receiving means being adapted to 1oe actuated in sequence by an interrogation si rtl from a utilization means;

a plurality of detection means `and anti-norm means, one being connected to each of said siom receiving means for detecting, delaying and transmitting an interrogation signal to an echo simulating system;

each of said detection means being electrically connected to one oi said plurality or" signal receiving means, and each of said anti-normalization means being electrically connected in series with the output of one of said detection means;

switch means connecting each of said plurality of signal receiving means alternatively to a dummy load or simulated echo output circuit in response to an output signal from said anti-normalization means; and

echo simulating means actuated by an. output signal from said anti-normalization means for generating an electrical pulse of a predetermined magnitude and time delay indicative of a hypothetical surface condition of a body or" water, whereby the generated simulated echo signal is transmitted from said echo Cai il@ simulating means, through one of said signal receiving means to a utilization means. 2. A system such as that deiined in claim l wherein; each of said anti-normalization means includes a multivibrator circuit for generating a time delayed puise simulating a time lag in the simulated transducer to which it is connected representing particular height of the simulated transducer relative to the normalization line of the system. 3. A system such as that deined in claim Z wherein; the signal receiving means to each of said simulated transducer channels com; lses two transmission lines; said detection means comprising a resistance in series with each of said transmission lines and a transformer sistance means to provide an output from sail tion means.

A system such as that dei-ined in claim including; an OR gate connected to the out-puts of the p ot anti-normalization means for tranen: output signal thereof to the echo simulating means. 5'. A system such as that deiined in claim l inclus ig; a relay driver connected to said CR gate and actuated by an output signal from said anti-normalization means; and relay means actuated hy said relay driver for positioning said switch means to connect said plurality or" signal receiving means to said dummy load prior to receipt of a signal from said anti-normalization means in said relay driver. o. A system such as that deiined in claim 5 'wherein said echo simulating means comprises;

coarse depth delay means connected to said GR gate for generating a signal delayed in time an amount approximately equal to the time delay of an echo traveling a redeterrnined distance from said simulated ransducer channels; said coarse depth delay means being selectively variahle to simulate a niultip icity of depths; line depth delay means coupled in series with the utput oi said coarse depth delay means for achieving an accurate time delay of said echo signal to indicate the simulated depth of said plurality of simulated transducer channels; said line depth delay means including a variable adjustment means for simulating wave motion; said line depth delay means including a signal means for indicating when the echo signal has neen delayed a desired length ot time to simulate a predetermined depth of said plurality of simulated transducers; oscillator means for generating an electrical signal to be utilized as an echo pulse; echo width pulsing means adapted to be actuated oy said signal means for determining the time duration of the echo pulse from said oscillator means;

thereby for enabling transmission of the echo only during the period of actuation of said echo width pulser;

attenuator means electrically connected to output of said gate means for attenuating the echo signal from said oscillator means in accordance with a tredctcrmined depth; and

output means including pulse amplifier means connected to said attenuator means for providing an output path for the echo pulse from said attcnuator means to one of said plurality of transducer channels so that the echo pulse may he transferred to the utilization means.

7. A system such as that defined in claim o wherein said I'ine depth delay means comprA s;

a run-down generator for generating an electrical signal which decreases linearly in magnitude with time;

trigger means having an input and an output;

said input being electrically connected to said coarse depth delay circuit, and said output being electrically connecte-d to the input of said run--down generator for actuating said run-down generator upon receipt of a signal from said coarse depth delay means;

comparator means connected to the output of said rundown generator means;

said comparator means having a reference voltage for comparison with the signal from said run-down generator means and being adapted to generate an electrical signal when the output ot said run-down gcnerator equals the reference voltage; and

resetmeans connected to the output of said comparator means for resetting said run-down genera-tor to thereby activate said echo Width pulse means when the output of said run-down generator equals the reference voltage of said comparator means.

S. A system such as that dened in claim 7 including;

electrical function generating means having an output signal electrically connected to the comparator means for super-imposing a predetermined function on said rererence voltage indicative of periodic variations of the similated depth of said plurality of simulated transducers to thereby vary the delay time for the echo signal.

9. A system such as that dened in claim including;

noise generating means having an output electrically connected to said comparator means for super-imposing a random signal on the reference voltage in said comparator means indicative of miscellaneous variations in the time delay of said echo signal.

liti. A system such as that defined in claim 9 wherein;

said attenuator means includes a coarse depth attenuation circuit; and

a fine depth attenuation circuit.

il. ln a system for simulating sonar echo signals indicating simulated waterdepth, the combination comprising;

coarse depth time delay means for generating a time delayed electrical signal approximately equal to the simulated Water depth in response to an electrical actuation signal;

said coarse depth time delay means having an input for receiving an actuation signal; and

an output for transmitting a time delayed pulse in respense to the actuation signal at the input;

ne depth time delay means electrically connected to the output or said 4coarse depth time delay means and adapted to be actuated by the output signal from said coarse depth time delay means foremitting a signal delayed in time with reference to the actuation of said coarse depth time delay means equal to that of said coarse depth time delay means plus an additional small amount inserted by said fine depth time delay means to thereby provide a time delay for simulated sonar echo signals substantially equal to the desired simulated water depth;

oscillator means for generating an electrical signal to be utilized as a simulated echo signal;

gate means electrically connected to the output of said oscillator for transmitting the output of said oscillator means for a predetermined length of time;

echo Width pulser means electrically connected to said gate means for actuating said gate means for a predetermined length of time in response to a signal from said ne depth time delay means;

attenuator means electrically connected to the output of said gate means for reducing they magnitude of output signal from said gate means a predetermined amount in accordance with the simulated Water depth; and

echo pulse output means electrically connected to the output of said attenuator means for transmitting the output signal of said attenuator means to a utilization means.

l2. A syste-m such as that defined in claim il. wherein;

said tine depth time delay means comprises;

a run-down generator for generating an electrical signal which decreases in amplitude linearly with time;

trigger means having an input and an output;

said input being electrically connected to said coarse depth time delay circuit, and

said output being electrically connected to the input of said run-down generator for actuating said run-down generator upon receipt of a signal from said coarse depth time delay means;

comparator means connected to the output of said rundown generator means;

said comparator means having a reference voltage from comparison with the signal from said run-down generator means, and being adapted to generate an electrical signal when the amplitude of the output signal from said run-down ge erator equals the reference voltage; and

reset means connected to the output of said comparator means for resetting said run-down generator when the amplitude of the output signal from said rundown generator equals the reference voltage to thereby actuate said echo Width puiser means to open said gate means.

i3. A system such as that dciined in claim 12 including;

electrical function generating means having an output electrically connected to said comparator means for super-imposing a predetermined function on said reference voltage indicative of periodic variations of the simulated water depth.

i4. A system such as that defined in claim i3 including;

noise generating means having an output electrically connected to said comparator means for super-imposing a random signal on the reference voltage in said comparator means indicative of miscellaneous variations in the simulated Water depth.

References Cited by the Examiner UNITED STATES PATENTS 9/55 Dickenson et al. 328-146 10/64 Feistman et al. 340-3 

1. IN A SONAR SURFACE SCANNER TRANSPONDER SYSTEM, THE COMBINATION COMPRISING; A PLURALITY OF SIGNAL RECEIVING MEANS SIMULATING TRANSDUCER CHANNELS, EACH RECEIVING MEANS BEING ADAPTED TO BE ACTUATED IN SEQUENCE BY AN INTERROGATION SIGNAL FROM A UTILIZATION MEANS; A PLURALITY OF DETECTION MEANS AND ANTI-NORMALIZATION MEANS, ONE BEING CONNECTED TO EACH OF SAID SIGNAL RECEIVING MEANS FOR DETECTING, DELAYING AND TRANSMITTING AN INTERROGATION SIGNAL TO AN ECHO SIMULATING SYSTEM; EACH OF SAID DETECTION MEANS BEING ELECTRICALLY CONNECTED TO ONE OF SAID PLURALITY OF SIGNAL RECEIVING MEANS, AND EACH OF SAID ANTI-NORMALIZATION MEANS BEING ELECTRICALLY CONNECTED IN SERIES WITH THE OUTPUT OF ONE OF SAID DETECTION MEANS; SWITCH MEANS CONNECTING EACH OF SAID PLURALITY OF SIGNAL RECEIVING MEANS ALTERNATIVELY TO A DUMMY LOAD OR SIMULATED ECHO OUTPUT CIRCUIT IN RESPONSE TO AN OUTPUT SIGNAL FROM SAID ANTI-NORMALIZATION MEANS; AND ECHO SIMULATING MEANS ACTUATED BY AN OUTPUT SIGNAL FROM SAID ANTI-NORMALIZATION MEANS FOR GENERATING AN ELECTRICAL PULSE OF A PREDETERMINED MAGNITUDE AND TIME DELAY INDICATIVE OF A HYPOTHETICAL SURFACE CONDITION OF A BODY OF WATER, WHEREBY THE GENERATED SIMULATED ECHO SIGNAL IS TRANSMITTED FROM SAID ECHO SIMULATING MEANS, THROUGH ONE OF SAID SIGNAL RECEIVING MEANS TO A UTILIZATION MEANS. 